Figure 4.

The establishment of a modified yeast two-hybrid system. (A) Schematic representation of the modified yeast two-hybrid system. (See text for detailed descriptions.) (B) Western blot analysis. Protein extracts from yeast cells expressing LexA-JH1 (lane 1), LexA-JH1-Stat1β (lane 2), LexA-JH1-Stat1(R602L) (lane 3), and LexA-JH1-Stat1(Y701F) (lane 4) were analyzed by immunoblot with antiphospho-Stat1 (Upper) and anti-Stat1c (Lower). (C) DNA-binding analysis. Protein extracts from B were incubated with the ³²P-labeled Stat1 DNA-binding probe followed by immunoprecipitation with anti-Stat1 antibody (5). The amount of bound DNA in each sample was measured directly by using a scintillation counter.